Seat adjusters are used on the front seat(s) of automotive vehicles to provide selective horizontal fore and aft, vertical and/or recliner movements of the seat. Such seat adjusters carry an upper support frame which supports the seat bottom and sometimes the seat back of the vehicle seat. The upper support frame is mounted on first and second, spaced track assemblies, each formed of an upper track which is connected to the upper support frame and which is slidably mounted in a lower track anchored to the vehicle floor. In a power seat adjuster, a drive mechanism, typically formed of a bi-directional electric motor, is mounted between the track assemblies and rotates a pair of drive shafts extending outward from the motor to a gear assembly or box mounted on each upper track. In one arrangement, the gear box rotates a lead screw extending below each upper track. A drive block mounted to the lower track threadingly receives the lead screw to cause reciprocal movement of the upper track and the attached upper support frame upon selective energization of the drive motor. Other drive mechanisms may also be incorporated into the power seat adjuster to provide vertical movement of the seat frame as well as pivotal movement of the seat back with respect to the seat bottom.
Although such seat adjusters provide easy fore and aft movement of the seat in the lower tracks, it is imperative that the seat remain in a fixed, stationary position during a collision, such as a frontal collision, in order to prevent injury to the passenger using the seat. As a result, the weight and size of the seat adjuster components are selected to provide a maximum amount of strength to resist any movement under the high impact forces transmitted to the seat through the seat belt during a vehicle collision. Thus, the individual tracks, the torsion tubes or bars typically extending between and interconnecting the spaced upper tracks into a rigid structure and the other components of the seat adjuster are made with stronger materials and greater thicknesses and dimensions to provide the requisite amount of strength.
In current usage, a fixed seat belt buckle mounting bracket is mounted on the rear end of one of the movable upper tracks. The seat belt buckle mounting brackets typically have an L-shape and are fixedly attached to the upper track by welding or by fasteners. One leg of the bracket is attached directly to the upper track, while the second leg extends integrally from the first leg upward from the upper track.
This arrangement provides a stiffener for the upper track as well as providing a retention device for attaching a fixed seat belt carrying a bracket which receives the tongue of a corresponding seat belt portion extendably and retractably mounted on a reel.
However, due to the attachment of the seat belt buckle mounting bracket on the upper track, forward movement of the passenger during a frontal vehicle collision exerts a load on the seat belt which is transferred through the seat belt buckle mounting bracket to the upper track of the seat adjuster. This load creates a high stress at stress riser points formed at the compound bend in the seat belt buckle mounting bracket between the first and second legs of the bracket. Any tool marks, cracks, etc., at the bend, which typically is formed with a relief, are subject to fracture under such loads.
Thus, it would be desirable to provide an upper track for a vehicle seat adjuster which has an improved seat belt buckle attachment means which overcomes the problems of previously devised seat belt buckle attachment means. It would also be desirable to provide an upper track of a seat adjuster having a seat belt buckle mounting bracket which is designed to change its geometry and/or position under load from a weak geometry position to a stronger geometry position. Furthermore, it would be desirable to provide a means for transferring load from the seat belt buckle attachment mounting bracket and upper track to the torsion bar assembly of the seat. It would also be desirable to gain higher loads during static loading, and greater reliability in the buckle system. In addition, it would be desirable to improve manufacturability by eliminating welds and reducing installation processing.